Richard Pryor Jr.: Nick Cannon Should Play My Dad ... If I Can't (VIDEO)

Richard Pryor Jr. has done a 180 and now feels Nick Cannon is the second most qualified guy to play his dad in an upcoming biopic ... second to him.

Pryor Jr. and his sister Rain previously told TMZ ... Cannon didn't have the chops to pull off the role. They thought Marlon Wayans was the right guy.

But Pryor Jr. just told our photog ,,, Cannon's passion for the role changed his mind and he now favors Cannon ... certainly over his step mom's choice, Terrence Howard.

Pryor Jr. also says the battle with stepmom Jennifer rages on.